Two-compartment vials in which a lyophilized medication and a solvent are held in complete independence from each other, have been in common use for packaging and mixing medications for many years. However, such use has been frequently marked by problems, some of which have related to the closure structure for the vial. In order to dislodge the center plug from between the compartments so that the solvent can be mixed with the medication, it is necessary to depress the stopper which is partially disposed in the neck of the vial and projects somewhat beyond the neck. However, the projecting portion of the stopper tends to bulge radially outwardly when depressed and therefore opposes insertion into the neck. Further, the harder the stopper is pushed into the vial, the more aggravated the problem becomes. On the other hand, if the stopper is made from less flexible or resilient material, in order to minimize bulging, then leakage of the solvent past the stopper readily occurs.
In an attempt to minimize or prevent bulging of the projecting stopper portion, U.S. Pat. No. 4,089,432 discloses a cap or closure structure wherein the projecting stopper portion is closely surrounded by a cylindrical sleeve which is attached to a vial mounting ferrule by means of a frangible connection. This connection must be broken in order to urge the sleeve and the stopper into the neck of the vial so as to displace the center plug. While the cap structure of this patent has proven to operate in a highly desirable manner, nevertheless in some instances it is undesirable to provide a cap having a frangible connection associated therewith.
The cap structure for the vial must be capable of closing and sealing the vial to prevent contamination of the medication therein. The cap structure must also be easily attached to the vial and must be capable of efficient and dependable activation when use of the medication is desired, which activation must be capable of accomplishment without causing contamination of the medication or of the syringe used for withdrawing it.
Accordingly, it is an object of the present invention to provide an improved closure structure specifically for a two-compartment vial. The closure structure involves a cap which surrounds and permits activation of the stopper sealingly seated within the neck of the vial, whereby activation of the stopper is more uniformly achieved while at the same time the stopper and the vial contents are maintained free of contamination. The cap additionally has locking structures associated therewith such that it is fixedly connected to the vial when in a non-activated condition, and is also similarly locked to the vial when in an activated position to permit secure handling of the vial, such as during insertion of a syringe through the stopper, without requiring removal of the cap.
In the vial and closure assembly of the present invention, the open or neck end of the vial has a resilient stopper sealingly seated therein, which stopper has a lower cylindrical portion of larger diameter seated within the neck. The stopper also has an upper projecting portion of smaller diameter, with the upper and lower portions being joined by an intermediate portion which defines a surrounding annular groove. A one-piece cap member surrounds the projecting portion of the stopper and is attached to the rim of the vial. The cap includes concentric inner and outer sleevelike skirts which are radially spaced apart and are joined together by a top wall. The inner skirt snugly surrounds the upper stopper portion and terminates in a lower locking flange which projects into the annular groove to prevent the cap from being axially removed from the stopper. This inner skirt is of slightly smaller diameter than the inner diameter of the neck so that activation of the vial causes the stopper and inner skirt to be axially slidably inserted into the neck. The outer skirt is axially longer than the inner skirt and, at the lower end thereof, has an inner locking flange which resiliently snaps beneath the annular rim of the vial to lock the cap thereto. The outer skirt also has a second locking flange on the inner surface thereof at a location spaced upwardly from the lower edge so that, upon activation, the cap is pushed downwardly so that the vial rim moves past the second locking flange, as permitted by limited resilient deformation of the cap, and snaps into position below the rim to positively lock the depressed cap to the vial.